Microtubules are ubiquitous structures among eukaryotic cells and play central roles in the development and vital cell functions. I am ultimately interested in the microtubule systems of cilia and flagella from the standpoint of the assembly of supramolecular cell organelles and the relationships of the structure to motility (i.e. wave generation and propagation). My short-range objectives in the proposed research project are to study the biochemistry and ultrastructure of purified proteins comprising and associated with the outer doublet microtubules (i.e., dynein, nexin bridges, radial spoke components and recently discovered components associated with specific regions of the doublet tubule). Conditions will be established for the reassembly of doublet microtubules and the reconstitution of subsidiary structures. The resemblance of these reconstituted systems to the intact organelle and the possible interaction of components will be investigated by examining the enzymatic and structural properties of the model system. In addition, image analysis techniques will be used to analyze the three-dimensional structure of the axoneme, negatively stained and imaged in the electron microscope. Such 3-D reconstruction methods will provide information concerning the relative phase relationships of the dynein arms and spokes and may provide information concerning structural interactions involved in microtubule sliding.